A great deal of attention has been focused by the packaging industry on efforts with twist container caps to achieve consistent closure sealing performance and consistent levels of capping torques. A basic problem exists with the construction of the closures and with the methods and machinery used to apply caps to containers. This problem results in large variations of the torque required by a consumer to remove such caps so that some demand unusual strength or special implements to open, while others may be so loosely applied that the effectiveness of their seal has been compromised. Thus, there has been a persisting need for container closures or caps which avoid such problems, and which have consistently superior closure sealing performance.
There also exists a persistant concomitant need for such superior container closures to have use or tamper evident features, such as an inner closure portion or seal on the container which can be punctured or easily removed to gain access to container contents therein supplying evidence of use, and afterwhich a cap can be placed over the resulting container opening to reseal the container and remaining contents.
It is particularly desirable that such an inner seal have seams formed by the periphery of the innerseal and an adjacent container body portion which are of high integrity and reliability, and which can withstand rigorous commercial application for use with products under pressure or vacuum.
It is therefore a general object of this invention to provide a container closure system with superior sealing characteristics. In particular, it is an object of this invention to provide a container neck finish with means for engaging a cap to provide such superior sealing characteristics. It is also an object of this invention to provide such a container having a use or tamper evident inner seal, which after opening or removal the open container neck can be resealed with a closure device, e.g. a cap, to provide the aforesaid superior closure sealing performance. It is an additional object of this invention to provide such an inner seal having container inner seal seams of high integrity and reliability, and able to withstand rigorous commercial application. It is still a further object of this invention to provide such a tamper evident inner seal which can be easily removed to provide convenient access to the container contents.